More than 200,000 Americans undergo hemodialysis in order to remove toxins from their blood, but to date there exists no device to monitor the efficiency of dialysis in real-lime. Such a device would be of great value in determining the dialysis state of both patients undergoing hemodialysis in a clinic and peritoneal dialysis at home. ChemSensing, Inc. (CSI) possesses a unique chemical detection technology in which colorimetric changes in an array of dyes constitute a signal much like that generated by the mammalian olfaction system; each dye is a cross-responsive sensor. This technology as been coined "Smell-Seeing." Previous work has shown that this technology can detect and quantify vapors (including alcohols, amines, ethers, phosphines, phosphites, thioethers and thiols) at the sub-ppm (parts per million) level. This Phase II program is designed to demonstrate that this technology is capable of detecting and quantifying sub-part per million levels of ammonia and therefore Provide an inexpensive, portable, and easily used real-time dialysis breathalyzer. The low cost of this technology makes it feasible for monitoring the efficiency of dialysis every session rather than just once a month, and its portability makes it feasible to monitor urea rebound on a regular basis.